The additional surveillance footage showed a new view of Dr. Mark Hausknecht, 65, and the suspect as they were riding bikes northbound along the city's Main Street before the shooting took place at 8:50 a.m. CT (9:50 a.m. ET) Friday, police said.

This is surveillance video from a Metro Lift bus traveling southbound on Main. The doctor and suspect are traveling northbound on Main. No other information at this time. Call HPD Homicide or @CrimeStopHOU if you can ID the suspect. All updates will be posted here. pic.twitter.com/eNwbA4zql6

An eyewitness who chose to not be identified said he helped Hausknecht shortly after the shooting occurred by propping the doctor's head with an orange traffic cone and saw the suspect ride away on a bike while others shouted for the man to stop, reported NBC affiliate KPRC.

The unidentified suspect was originally described by a witness as wearing a grey warm-up jacket. The new photos show the man wearing a blue, short-sleeved polo shirt, a khaki baseball hat and khaki shorts with an olive green backpack, according to police.

Former President George H.W. Bush leaves Methodist Hospital with his cardiologist, Mark Hausknecht, after a news conference in Houston in 2000.David J. Phillip / AP file

Some of Hausknecht's friends and neighbors have attempted to help police find the suspect.

Dr. Sally Miller and others were canvassing residents, going door-to-door and asking if people may have seen anything suspicious Friday morning and whether they have security footage of the street from that time, according to KPRC.

Hausknecht is "a neighbor and he's a colleague of my husband's, and we want to solve this murder — a senseless murder," Miller told the station.

After the shooting, Hausknecht was brought to Ben Taub Hospital, a trauma center, and pronounced dead, said Houston police Assistant Chief Troy Finner.

Hausknecht was a popular cardiologist at the DeBakey Heart & Vascular Center and the Houston Methodist Hospital, officials said.

CORRECTION (Aug. 3, 2018, 11:45 p.m. ET): An earlier version of this article misstated the name of a center where Hausknecht worked as a cardiologist. It is the DeBakey Heart & Vascular Center, not the DeBakey Heat & Vascular Center.